Carolina northern flying squirrels are uncommon in the park. Preferred habitat consists of spruce-fir forests and mixed conifer-northern hardwood forests. Flying squirrels are nocturnal and active throughout the year, although they may remain inactive for several weeks at a time during severe winter weather. Carolina northern flying squirrels nest communally during the colder months.
The Carolina northern flying squirrel inhabiting the southern Appalachians (Glaucomys sabrinus coloratus) is listed as an endangered species by the U.S. Fish and Wildlife Service.

Species Measurements:
- Adult Total Length: 255-275 mm (10-11 in.)
- Tail: 100-130 mm (4-5? in.)
- Hind Foot: 36-40 mm (1?-1⅝ in.)
- Weight: 110-185 g (4-6? oz.)

Physical Characteristics:
Except for being larger, the Carolina northern flying squirrel appears similar to the Southern flying squirrel (Glaucomys volans). Both have brownish upperparts and whitish underparts. Whereas the belly hairs on the Southern flying squirrel are white to their base, the bases of the belly hairs of the Carolina northern flying squirrel are usually grayish. The tail appears to be dorsoventrally flattened. A loose fold of furred skin connects the front and hind limbs from the wrists to the ankles.

These squirrels cannot fly. Rather, they glide from a higher perch to a lower one. In doing so, they spread their legs, thus drawing taut the loose skin running along each side of the body. The membranes support the squirrel as it glides in somewhat the same fashion as a parachute. The tail acts as a rudder. By varying the tension on their membranes, and by altering the position of their tail, flying squirrels can control their direction and speed to some extent. They always land in a head-up position on the trunk of a tree.

Habitat:
Preferred habitat consists of spruce-fir forests and mixed conifer-northern hardwood forests. Handley (1953) stated that this squirrel is "irregularly distributed at high elevations in the spruce and balsam cloud forests of the southern Appalachian Mountains." The specimen from Blanket Mountain, however, was found in a deciduous forest "at least seven airline miles from the nearest spruce and fir" (Handley, 1953).

Reproduction:
Most flying squirrels probably breed for the first time when they are about a year old. The breeding season varies with latitude, occurring from spring to fall in the north, and from late summer to winter in the south. At any given locality, there are usually two peaks of breeding that reflects the difference in the timing of the first breeding of earlier- and later-born females of the previous year. Nests are composed primarily of shredded yellow birch bark, moss, and grass, and are usually in a tree cavity or a woodpecker hole (Muul, 1969).
A single female was found near Walker Prong on August 22 (Linzey, 1995b). At birth, young squirrels weigh about 5 to 6 g, and are blind and hairless except for vibrissae and short hairs on the chin and snout. The ears, which are folded over and sealed at birth, become erect between two and six days of age. By seven days hair is visible over most of the body. The eyes open at about 31 to 32 days of age, by which time the young are fully furred, and their locomotion and coordination are well developed. Weaning occurs at about 60 days. When they are about 12 weeks of age, the young begin a molt from the juvenile to the first adult pelage. At this age they are usually still associated with their mother, and may stay with her until she has another litter. Families frequently remain together over winter.

Longevity:
Life expectancy in the wild is probably less than four years (Jackson, 1961).

Terrestrial Ecology:
Flying squirrels are nocturnal and active throughout the year, although they may remain inactive for several weeks at a time during severe winter weather. Northern flying squirrels nest communally during the colder months. This communal behavior is thought to either be a behavior for heat conservation, and/or a social or physiological function.

Feeding behavior:
In the southern Appalachians, Carolina northern flying squirrels feed mostly on lichens (Ascomycetes), mushrooms (Fungi), seeds, buds, fruit, conifer cones (Pinales), meat, and arthropods (Arthropoda) (Weigl, 1977). They appear to be more carnivorous than many other squirrels; eating insects (Insecta) and other invertebrates, birds eggs and nestlings (Aves), mice (Rodentia), and carrion. In the fall, they are active in hoarding acorns (Fagaceae) or other kinds of nuts. The nuts are typically cached in crevices or cavities in tree trunks.

Predators and Defense:
No predators recorded from the park.

Parasites:
None recorded in the park.

The Northern flying squirrel ranges from eastern Alaska and Canada, south through New England and the Great Lakes region. Its range continues south along the Appalachian Mountains to western North Carolina and eastern Tennessee. However, south of Pennsylvania, Carolina northern flying squirrels exist only in isolated high elevation populations. In the western United States, the Northern flying squirrel range extends southward in the mountains to southern California and Utah.

Carolina northern flying squirrels are uncommon in the park. The first individual was taken on Blanket Mountain (4,000 feet) southwest of Elkmont, on February 20, 1935 (Handley, 1953). In 1980, 40 nest boxes were erected in five areas from Newfound Gap to Clingmans Dome, and in two areas on Balsam Mountain to determine the status of this species in the park (Linzey, 1984). The boxes were used by Southern flying squirrels (Glaucomys volans) and Red squirrels (Tamiasciurus hudsonicus), but not by Carolina northern flying squirrels. However, eight Carolina northern flying squirrels were captured, marked, and released near Indian Gap during 1987 and 1988 (Weigl, Knowles, and Boynton, 1992).

References:

Handley, C.O., Jr. 1953. A New Flying Squirrel from the Southern Appalachian Mountains. Proceedings of the Biological Society. Washington 66: 191-194.

Heaney, L. R. 1999. Northern Flying Squirrel. Pages 462-463. In: D.E. Wilson, and S. Ruff (eds.). The Smithsonian Book of North American Mammals. Smithsonian Institution Press, Washington, D.C.

Linzey, D. W. 1984. Distribution and Status of the Northern Flying Squirrel and the Northern Water Shrew in the Southern Appalachians. The Southern Appalachian Spruce-Fir Ecosystem: Its Biology and Threats. National Park Service Research/Resource Man

Linzey, D. W. 1995a. Mammals of Great Smoky Mountains National Park. The McDonald & Woodward Publishing Company, Inc., Blacksburg, Virginia.

Muul, I. 1969. Mating Behavior, Gestation Period, and Development of Glaucomys sabrinus. Journal of Mammalogy 50(1): 121.

Weigl, P.D. 1977. Glaucomys sabrinus coloratus Handley. Carolina northern flying squirrel. Pp. 398 - 400 In: Cooper, J.E., S.S. Robinson, and J.B. Funderburg (editors). Endangered and threatened plants and Animals of North Carolina. Raleigh: North Ca

Weigl, P.D., T.W. Knowles, and A.C. Boynton. 1992. The Distribution and Ecology of the Northern Flying Squirrel, Glaucomys sabrinus coloratus, in the Southern Appalachians. Final Report to U.S. Fish and Wildlife Service.

Wells-Gosling, N. and L.R. Heaney. 1984. Glaucomys sabrinus. Mammalian Species No. 229: 1-8. American Society of Mammalogists.

Linzey, D. W. 1995b. Mammals of Great Smoky Mountains National Park-1995 Update. Journal of the Elisha Mitchell Scientific Society 111(1): 1-81.

Fleetwood, R. J. 1934-35. Journal of Raymond J. Fleetwood, Wildlife Technician, Great Smoky Mountains National Park, for the period May 27, 1934 - June 27, 1935. 499 pp. (Typewritten).